Method of making flexible corrugated tubular metal walls



Aug. 21, 1934. w. M. FULTON METHOD 01'" MAKING FLEXIBLE CORRUGATEDTUBULAR METAL WALLS Filed larch 31, 1930 2 Sheets-Sheet 1 W% m l.l|lllllalllll H lllllllll I -:52: r ill v I Aug. 21, 1934. M, FULTON[1,970,650

mmnon 'OF'M-AKING FLEXIBLE CORRUGATED TUBULAR METAL WALLS Filed March31, 1930 2 Sheets-Sheet 2 1 anvenloz $3M Qmm Mm $1 4M Patented Aug. 21,1934 METHOD OF MAKING FLEXIBLE CORRU- GATE!) TUBULAR METAL WALLS WestonM. Fulton, Knoxville, Tenn, assignor to The Fulton Sylphon Company,Knoxville, Tenn., a corporation of Delaware Application March 31, 1930,Serial No. 440,582

1 Claim.

This invention relates to flexible, corrugated, tubular metal walls andmethods of making the same.

It has heretofore been proposed to make flex- 5 ible, expansible andcollapsible, tubular metal walls by shaping annular members and unitingthem in series, alternately at their inner and outer peripheries, so asto make up a bellowslike structure. Structures of this character asheretofore produced, however, have been provided with soldered, crimpedor analogous joints at the outer and inner peripheries of the annularmembers, so that the stresses existing during expansion and contractionof the bellowslike structure have been concentrated at these soldered,crimped or other joints, with the result that such joints have failedafter a relatively small number of flexures.

It has also been the practice to make flexible,v

corrugated, tubular metal walls by forming relatively deep corrugationsin a single piece of metal drawn or otherwise formed to tubular shape,and structures of this character have been capable of withstanding arelatively great number of flexures without rupture, but in order todeform a tube of relatively thin metal into deeply-corrugated shape ithas been necessary to deform the, metal progressively by smallincrements so as to prevent overstressing of the metal, withintermediate annealing operations, so that the cost of manufacture hasbeen relatively high by reason of the number and character of operationsinvolved.

It is an object of this invention to provide a flexible, corrugated,tubular metal wall, and a method of making the same, whereby the wallmay be composed of separate elements that may be formed and connected bya minimum number of simple operations so that the cost of manufacturemay be reduced, and yet the wall will be capable of withstanding arelatively large number of fiexures.

Another object of this invention is to provide a flexible, corrugated,tubular metal wall of the character referred to, and a method of makingthe same, whereby the wall may be made of any desired length and at thesame time it will apcharacter referred to, and a method of making thesame, whereby some of the movement at the bends of the corrugationswhich accompany expension and contraction of the wall is in the form ofslippage between the elements of the wall instead of by bending entirelyas in the case of walls made from one piece of metal.

Another object of this invention is to provide a flexible, corrugated,tubular metal wall of the character referred to, and a method of makingthe same, whereby walls of this character may be inexpensively producedfrom metal elements that are not sumciently large to be employed in themanufacture of one-piece walls, so that small pieces of metal may beutilized in the production of walls of this character.

Other objects will appear as the description of the invention proceeds.I

The process of the present invention is capable of being carried out ina variety of ways and the product of the present invention is capable ofreceiving a variety of mechanical expressions, an exempliflcation of theprocess and product being hereinafter described and illustrated on thedrawings, but it is to be expressly understood that the drawings are forpurposes of illustration only and are not to be'construed as adeflnitionof the limits of the invention, reference being had 0 to theappended claims for that purpose.

Referring in detail to the drawings wherein the same referencecharacters are employed to designate corresponding parts in the severalfigures:

Fig. 1 is an axial section of one of the two sizes 35 of metallicelements which go into the production 01 a flexible, corrugated, tubularmetal wall embodying the present invention;

Fig. 2 is an axial section of-the blank of Fig. 1

' after the first operation thereon;

Fig. 3 is an axial section of the other size of element used;

Fig. 4 is an axial section of the blank 01 Fig. 3 after the firstoperation thereon;

Fig. 5. is an axial section illustrating how the elements of Figs. 2 and4 are connected;

Fig. 6 is an axial section to illustrate how successive elements may beconnected; I

Fig. 7 is a diagrammatic view illustrating how the blank of Fig. 2 maybe formed from the blank of Fig. 1;

Fig. 8 is a diagrammatic view illustrating how the blank of Fig. 4 maybe formed irom the blank of Fig. 3; h

Fig. 9 is a diagrammatic view illustrating how the blanks of Figs. 2 and4 may be connected; and

Fig. 10 is a diagrammatic view illustrating how successive pairs ofelements may be connected.

A flexible, corrugated, tubular metal wall is built up of a plurality ofannular elements which V are so interrelated by mechanical joints thatthe elements are interlocked by curved surfaces of relatively largeradius of curvature, which preferably permit relative movement axiallythereof. 5 These elements, as hereinafter explained, are made of twosizes, and the elements of different size are connected in alternationuntil a flexible, corrugated, tubular wall of the desired length isobtained. The elements may be made of any suitable material, and of anysuitable size and thickness to produce a wall of the desired crosssectional area and flexibility. The form which the elements take willvary with the desired cross section of the resulting wall (whethercircular, elliptical, polygonal, etc.), and these elements may be madein any suitable way, as by drawing the blanks from annular disks,cupping circular disks and "punching out the central portions thereof,etc.

Fig. 1 illustrates one of the two sizes of blanks and Fig. 3 illustratesthe other of the two sizes of blanks that are employed. The blank 10 ofFig. 1 is of annular formation and has an axially extending flange 11 atits outer periphery and 25, an axially extending flange 12 at its innerperiphery, the two flanges being connected by a radially extendingportion 13 of suitable width to secure the desireddepth of corrugationas will be apparent from the following explanation. The

blank 14 is of smaller size but similar shape, be-' ing provided with anaxially extending flange 15 at its outer periphery, an axially extendingflange 16 at its inner periphery and an intermediate radially extendingportion 17 connecting said 5 flanges. The flange 15 has a smallerdiameter than the flange 11 and the flange 16 has a smaller diameterthan the flange 12.

The flange 12 on element 10 is bent into a generally semi-circular formas shown in Fig. 2. This shaping of the flange 12 may be effected in anysuitable way, as by rolling, spinning, die pressing, etc., Fig. 7showing more or less diagrammatically a suitable pair of rolls foreffecting this bending'operation. The roll 18 is provided with aradially extending flange 19 of suitable width and curved at-itsperipheral portion 20 to conform with the curvature to be given to theouter face of the flange 12. Roll 21 is provided with a pair of flanges22 and 23, the former of 0 which projects radially to a greater distancethan the latter, and said rolls are shown as connected by a flllet 24corresponding with the curvature to be given to the inner face of theflange 12 when the bending operation is to be continued until the curvedflange is bottomed on the roll 21, although [this is not essential, asthe bending operation can be discontinued before the flange 12 bottomson the surface connecting the flanges 22 and 23, in which event saidconnecting surface need not 0 conform to the curved surface to be givento the inner face of the flange 12. The flange 22 owing to its greaterdiameter than. the flange 23 acts to guide the portion 13 of the element10 durin the bending operation.

85 Element 14 may; then be associated with the element 10 in the mannerhereinafter explained and the flange 15 thereof be bent subsequently tosuch connection, but I prefer to bend the flange 15 as shown in Fig. 4before associating element 14 0 with element 10. This bending operationmay also be done in any suitable way as heretofore pointed out, Fig. 8showing apair of rolls for performing this operation. Roll 25 isprovided with a flange'26 having its periphery curved at 27 to conformwith the curvature to be given to the inner face of the flange 15, androll 28 is provided with a pair of flanges 29 and 30, flange 29projecting beyond flange 30 to guide the portion 1'7 of element 14during the bending operation, as heretofore explained. If the bendingoperation is to be continued until the flange 15 is bottomed, aspreferred, the flanges 29 and 30 are connected by a fillet 31 conformingto the curvature to be given to the outer face of the flange 15.

The curvature given the flanges 12 and 15 may vary within considerablelimits and as hereinafter explained may be greater than that desired inthe final wall, or it may be selected in conformity with the desiredfinal curvature of the corrugations, in which event the curvatureselected should be of generally semi-circular shape passing smoothlyinto the lateral wall formed by the section 13 or 17. The radii ofcurvature are therefore relatively large and as hereinafter explainedthe curved surfaces thereby formed are preferably coextensive with thedesired spacing of the lateral walls of the corrugations.

At this stage of the operations flange 16 of element 14 should fitslidably within thecurved flange 12 of element 10, and flange 11 ofelement 10 should fit slidably over the curved flange 15 of element 14.The two elements 10 and 14 may be connected at either their outerflanges or at their inner flanges. I have shown them connected at theirinner flanges, and to this end flange 16 is inserted into flange 12 asillustrated in Fig. 5, and then flange 16 is bent in any suitable way toembrace the curved flange 12, as illustrated in Fig. 6. Flange 16 shouldbe of such length that it will extend approximately through more than 90of curvature, and preferably through substantially 180 of curvature, toembrace the curved flange 12 as shown, and when so bent into contactwith curved flange 12, the two elements 10 and 14 are interlocked so asto prevent disconnece 115 tion of thesame. Referring to Fig. 9 I haveillustrated a pair of rolls 32 and 33 for connecting the elements 10 and14, roll 32 being provided with a flange 34 curved at its periphery 35to conform with the curvature of the outer surface 12 of flange, 12, androll 33 being provided with a pair of flanges 36 and 37 connected by aflllet 38 where the rolling operation is to be continued until bottomingoccurs. Flange 36 extends to a greater radial distance than flange 3'7so that the portion 17 of element 14 is guided during the bendingoperation, but-if desired the roll 33 may be made in theform of theupper roll illustrated in Fig. 10 so that the portion 13 of the element10 will also be guided during the bending operation. After a pair ofelements 10 and 14 have been associated as shown in Fig. 6 an element'10 may be mechanically connected thereto, and then an element 14connected to the second element 10, and so on until a wall of thedesired length is built up, but I prefer to connect the elements 10 and14 in pairs as heretofore explained, and then connect the pairs togetheruntil a wall of the desired length is built up. Whichever of theseprocedures is followed, the flange 11 of the second element 10 is bentaround the curved flange 15 of the element 14 analogously as flange 16is bent around the curved flange 12 so as toproduce a mechanicalinterlock extending over more than 90 of 'surface of the bend to preventsubsequent 145 disconnection of the elements. This bending operation mayalso be accomplished in any suit-' able way, Fig. 10 illustrating a pairof rolls 39 and 40 for performing this operation. Roll .39 is providedwith a pair of flanges 41 and 42 connected by a fillet 43 when thebending is to be continued until bottoming occurs, and roll 40 isprovided with a pair of flanges 44 and 45, shown as connected by afillet 46 to receive the formed bend on the second element 14 althoughthis is not essential. Flange 41 preferably projects to a greater radialdistance than flange 42 and flange 44 preferably extends to a greaterradial distance than flange 45, so as to provide radial surfaces on therolls which coact with and guide the radial surfaces on the elements 10and 14 during the bending operation. These radial faces on the rolls mayalso be utilized to effect a planishingaction on the radial surfaces ofthe elements, which has been found to have a beneficial eifect.

By continuing this procedure successive elements 10 and 14 or succemivepairs of elements 10 and 14 may be mechanically connected together bybending their flanges into a mechanical interlock as heretoforeexplained until a wall of the desired length has been built up. Ifparticular forms of end members are desired at either or both ends ofthe flexible wall, they may be formed in any suitable manner to have thedesired shape, size, character, etc., and provided with a flange forconnection to the proper flange 12 or 15 of the end elements of theflexible wall in the manner heretofore described. In making thesemechanical joints between the successive sections, or after the jointshave been made, a lubricant, such as graphite, may be interposed betweenthe curved surfaces so as to facilitate their sliding one over theother. Also, if desired, means may be associated with the mechanicalconnections so as to seal the joint therebetween and render them fluidtight.

While I prefer to formthe elements so that when connected in the mannerheretofore described they constitute a flexible, deeply-corrugated,tubular metal wall of the final. dimensions desired, this is notessential, as the corrugations may be subsequently deepened or narrowedor both, or otherwise changed in shape; by cold working or otheroperations, such for example as by subjecting them to rolling operationsof the character disclosed in my Patent No. 971,838, granted October 4,1910, for Process of making tubular metal walls, during which operationstemper and toughness may be worked into the bends of the corrugations,as desired.

It will therefore be perceived that a flexible, corrugated, tubularmetal wall and process of making the same has been provided whereby thewall may be made up of separate elements which may be formed andconnected by a,minimum number. of simple operations so that the cost ofmanufacture is reduced, and so that the wall may be made at a minimumexpense from small pieces of metal. At the same time the resulting wallapproximates in its characteristics the singlepiece, highly-flexible,deeply-corrugated, tubular metal wallsheretofore produced, because themechanical joints'between the elements do not produce high localizedstresses and early rupture,

as has been characteristic of the soldered, crimped and similar jointsused in the prior art. The flanges are interlocked along curved surfacesof relatively large radius of curvature, and when the resultingcorrugations have substantially parallel lateral walls at right anglesto the axis, the sums of the radii of curvature of the mating flanges ispreferably substantially equal to the axial spacing of said lateralwalls.

Owing to the semi-circular curvature of the interlocking elements at therespective bends, the interengaged bends tend to slide over one anotherduring expansion and contraction of the wall, so that the stresses atthe bends are less than if the metal were integral. This relativemovement between the respective elements therefore tends to facilitateexpansion and contraction of the wall,

and this may be increased by interposing a lubricant between the slidingsurfaces. The elements may also be made free to have circumferentialmovement with respect to each other. This manner of procedurealsopermits a wall to be formed of any desired length, and by cold workingor other operations the bends may be subsequently deepened or narrowed,or both, or given the desired shape or the desired degree of toughness,temper, etc. ated with the joints for rendering them fluid tight, ifdesired, a suitable construction to this end being disclosed in theapplication of Jean V. Giesler, Serial No. 191,826, filed May 16, 1927,entitled Flexible corrugated tubular walls.

While one method of procedure and one product Means may also be readilyassociembodying the present invention have been described withconsiderable particularity, it is to be expressly understood that theinvention is not restricted thereto, as the invention is capable ofbeing carried out in other ways and of receiving other expressions, someof which will now readily suggest themselves to those skilled in theart, while changes may be made in the order and details of the steps andin the details of construction, arrangement and proportion of parts,without departing from the spirit of this invention. Reference istherefore to be had to the claim hereto appended for adeflnition of thisinvention.

What is claimed:

The method of making a flexible corrugated tubular metal wall whichincludes the steps of forming annular elements with axially directedflanges at the inner and outer periphery of each element, alternatelytelescoping the inner and outer flanges of succeeding elements, androlling each engaged .pair of flanges while in telescopic engagementinto arouate bends curved in the direction of the axis into asubstantially semicircular curvature of sufilcient extent to interlockthe overlapping curved surfaces against separation within the range oftheir possible relative movement while at the same time providingrelatively

